1. Field of the Invention
The present invention relates to a solid-state imaging apparatus, and particularly relates to a solid-state imaging apparatus having an A/D converting circuit provided in each of columns and subjecting a plurality of obtained digital signals to arithmetic processing, and a method for driving a solid-state imaging apparatus.
2. Description of the Related Art
The so-called horizontal skipped reading (hereinafter regarded as the same meaning as horizontal skipping operation) has been known in a conventional solid-state imaging apparatus. In the horizontal skipped reading, for example, an analog electric signal, obtained by converting an incident light in each pixel, is read out in every other column of the pixels arranged in a matrix in a use of requiring a high speed operation, such as in a moving image.
In addition, a method is disclosed in Japanese Patent Application Laid-Open No. 2006-025189, which installs an A/D converting circuit in each column of pixels, and subjects the digitized signal to arithmetic processing. Specifically, the patent describes an image sensor which has two register circuits provided per pixel column to store two different signal levels from the same pixel into the register circuits and calculates a difference between both of the signal levels in a digital region.
When a horizontal skipping operation is performed and operations are performed on the basis of the signals held in the plurality of respective register circuits in the circuit configuration disclosed in the aforesaid Japanese Patent Application Laid-Open No. 2006-025189, the AD converters and register circuits in the skipped, that is, not read out, columns become the state of not participating in the operations. In this point, the circuit is susceptible to investigation in terms of use efficiency.